Encyclopedia mode
Get the Monster Tome relic during game play to unlock the "Encyclopedia" option at the "Secret Info" menu, which details all monsters that you have defeated.

Summoning Tome
Go to Castle B's Skeleton Cave. First, have the Griffin's Wing and go into the double exit save room near the entrance area with the big pillar. While in the save room, save the game then use the Griffin's Wing and go through the roof. You will get Wizard's Urn and Summoning Tome.

Gradius reference
When you combine the Bolt Spellbook with the Bible secondary weapon, your character will have a double orb shield in front of him. This shield is one of the shields from Konami's classic Gradius series, with similar sound effects when it collides with enemies.

Glitch: Keep relics
Get all of the Dracula relics and go to Castle B. Equip both the JB and MK Bracelets. Go down into the room and you will start fighting Maxim after talking to him. Defeat Maxim and all the Dracula relics will start flying around and Dracula Wraith will appear. When the battle starts, enter the pause menu and go to "Relics". You will see that you still have all of the Dracula relics, even though they flew away and made Dracula.

Maxim Spells
The same spell that will call duplicate Maxims to fight enemies will summon a healing when all alone. Just face right, & in one continuous motion, push LEFT,DOWN, RIGHT, DOWN, LEFT + B. Thanks to NeT1Bler for the summoning directions. This spell will enable you, as Maxim, to travel further and not to have to worry so much about getting to a Save Point.

Play as Maxim Kischine
Enter MAXIM as a name after completing the game at least once. He is faster and jumps higher than Belmont.

No magic
Enter NO MAGIC as a name after completing the game at least once.

Hard mode
Enter HARDGAME as a name after completing the game at least once. A voice can be heard at the start of the introduction to confirm correct code entry.

Boss Rush mode
Successfully complete the game to unlock the Boss Rush option. There are three levels (easy, normal, and hard) that must be unlocked by playing each in succession, starting with easy.